


Sweet Dreams, Aniki

by Illuminous_Anonymous



Category: Undertale (Video Game)
Genre: Consent, M/M, Mildly Dubious Consent, Praise Kink, Sibling Incest, Somnophilia, Weird Biology, Xenophilia
Language: English
Status: Completed
Published: 2018-12-17
Updated: 2018-12-17
Packaged: 2019-09-20 23:56:34
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,953
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/17032347
Author URL: https://archiveofourown.org/users/Illuminous_Anonymous/pseuds/Illuminous_Anonymous
Summary: There’s something about the lack of stress and the openness in Sans’ sleeping form that called out to Papyrus’ magic. Something about his older brother being safe, warm, and happy caused a tingle in his chest…and strangely enough, his groin.





	Sweet Dreams, Aniki

**Author's Note:**

> ah, well, while i'm logged out of tumblr, i figured i'd copy over some of my tumblr fics.
> 
> here's another one.
> 
> originally published April 21, 2017 at the asscrack of 1am

Papyrus stared nervously at his brother as he snoozed on the couch, listening to the skeleton breathe without lungs. Sans’ arm was draped across the armrest on the end of the couch close to the stairs, his small body unable to completely cover both seats. In his sleep, he’d rolled around enough for his tank top to ride up, his tantalizing spine peeking up at Papyrus as the shirt shifted with the expansion of Sans’ rib cage.

Papyrus swallowed down some saliva he hadn’t noticed form.

He and his brother had a more romantic relationship than most siblings did. While Sans had previously thrown all possibilities of such out of his mind, proclaiming to himself that his thoughts were much too dirty to spread to his beloved younger sibling, he’d had no idea until five months ago that Papyrus did, in fact, have the capacity to moan names into his pillows when his baser desires bubbled up too much to be ignored. Well, one name in particular.

After pussyfooting around him for the greater half of another month, Papyrus got just annoyed enough to address the situation forcefully enough with Sans that he couldn’t teleport away. They discussed their feelings–as much as Sans would disclose, but Pap was working on that–and realized the possibilities of a mutual relationship. It required a little time to dissuade Sans from any of his more negative thoughts about himself and his influence over his very much 22-year-old brother, but it was worth it.

From there was the start of a beautiful relationship…though Papyrus hadn’t imagined that Sans would be so coy. The skeleton’s face would flush blue at the slightest hint of a kiss, and holding hands about made him turn into a berry. It was such a juxtaposition of how dirty Sans’ thoughts about him apparently were, and he was starting to doubt that Sans was as bad as he’d said he was. Until he’d given him permission to touch him lewdly whenever they were at home alone.

How had he’d said it? “this land is your land” or something.

Papyrus made it a two-way street, avid in his allowance for his brother to also let loose. Sans had acted on it a few times, hugging his brother low on his waist or letting his hand wander down his back. He returned the sentiment many times over though, taking a hold of his brother’s hip as they kissed on the couch, rubbing gloved hands on the sides of his waist when Sans had his back turned, offering Sans the chance to sit on his lap (which he took every time) only to molest him by holding his chest while kissing along his neck bones, among other things.

So now, watching his brother’s small frame shift and snore lightly, he wondered if the “everything goes at home” idea extended to when they weren’t conscious.

His train of thought derailed a little when Sans shifted, turning more onto his back with a sigh. His shirt failed to droop onto his spine, letting Papyrus know that Sans was just unconscious enough to lose a handle on his magic, his ecto body not completely visible, but still there. The hand not draped over the armrest moved down and scratched at his stomach, just to accentuate that fact apparently.

Papyrus looked off to the side out of personal embarrassment. Really, was he that lewd as to look at his brother’s unconscious body and find him arousing? It made no sense. He was the same as always, just as small, round, and plush as he was when awake, and Papyrus didn’t always feel the same drive he did now. It had to be that, just at this particular moment in time, he was turned on. Which happened sometimes. That made sense.

His sockets trailed back over to look at Sans’ face. His grin had smoothed out in neutrality, barely a smile at that point, but somehow that made him look more comfortable than he usually seemed. His shoulders were lax in a cattish way, sockets dipped closed softly against his cheekbones, bruise-burned from too many years of not enough sleep. 

Papyrus had become close enough to Sans by now to recognize when he was in a deep sleep compared to a light, semi-conscious doze; the more relaxed he was, the further gone he was, and Sans was gone. He exuded comfort and restfulness, safe enough in his home with his brother to actually sleep, and at that moment it made Papyrus horny as hell.

The tall skeleton clenched his fists at his side as he started stepping forward, approaching his defenseless brother.

Sans didn’t move an inch, completely dead to the world, as Papyrus stood over him.

He would’ve realized the rush of power that ran down his spine probably shouldn’t have happened had he been thinking properly.

Nevertheless, he shifted himself into the empty spot on the couch, moving Sans’ legs carefully to accommodate his body between them. When Sans didn’t move, barely making a sound in his slumber, Papyrus leaned forward, pelvis to pelvis, bending over his older brother’s lax body. Softly, he pressed his teeth against the other’s in a kiss, a little magic sparking from the contact. His soul warmed with the way Sans’ grin twitched lightly.

“You’re so cute,” Papyrus mumbled. While he wouldn’t have been able to say such a thing with his brother awake, compliments whispered while the other was unconscious went without debate. It filled Papyrus with determination, for some reason, to shower his brother with praises and pleasure that he couldn’t deny.

So, he leaned down a little and started kissing Sans’ neckbones, pressing his teeth against the cartilage as his hand trailed down the skeleton’s pudgy body.

“You’re always so nice to touch,” Papyrus whispered, kissing another bone, “Skeletons are always soft, but you’ve always been the softest.”

Sans sighed, cheekbones warming a little, and Papyrus wondered for a moment if he was awake. But sighing was all the other did, so he continued, his hand reaching the other’s hips. He thumbed around on the Sans’ magical plushness there, enjoying the feeling as he moved down to the other’s collarbones.

“mmmh…”

Papyrus flicked his gaze up to his brother’s face again, a warm feeling spreading through his chest. Was this something else that Sans couldn’t hold back when asleep? He was always so quiet whenever they were doing something lewd, but… Maybe he couldn’t do that now. It made his actions that much more alluring.

The tall skeleton formed his tongue and started licking and nibbling the other, lathing his saliva over the small magic bruises that formed. Sans mumbled again, turning his head a little to bare his neck unconsciously, and, of course, Papyrus would’ve been rude to not take the invitation.

As he marked up his brother’s neck, the hand caressing the other’s hip moved down in between his legs, his arm bending a tad awkwardly to reach his prize.

“mmmuuhh…ahhh…”

Sans couldn’t help but groan as Papyrus pressed down onto his core, his magic having chosen a form in his sleep.

“So naughty…are you enjoying this too, Sans?” Papyrus mumbled, pressing down further onto the other’s squirming cock, “You certainly seem to be. I think you deserve a little extra touch…”

He grinned against his brother’s neck as he began pulling his shorts down before he backed up to take them off. He slipped them off fairly easily, and lidded his sockets when he noticed his brother had foregone wearing underwear.

“Geez Sans, how lewd,” he grinned, admiring his favorite shade of blue flushing further over Sans’ face in his sleep, even as his lower half was very much awake.

He and his brother knew very well how to make different kinds of genitals for whatever needs they wished to fill. Different kinds meant a lot of experimentation and finding one’s favorite. In Sans’ unconscious mind, that apparently was a tentacle, the organ shifting as it left a lighter trail of blue on his stomach from leaking at the tip, and a hole, perfect for entry, lower down.

He reached up, taking the other’s tentacle into his hand. His heart warmed giddily when the tip of it started to curl around him, almost like it was greeting–he knew Sans’ magic was simply looking for stimulation, but he didn’t mind. A part of him wanted to kiss it, but perhaps he could do that at a later time. Instead, he knew he had a different idea.

Papyrus watched Sans’ face as his gloved hand started shifting up and down the twitching organ, careful to make sure he didn’t go too fast as to wake the other.

The slide quickly became very easy–Sans was already pretty wet, having dripped cum against himself–and Papyrus started to gather some of it to use on the rest of him. Sure, he could get up and go get the lube, but that would require getting up. And who knew how much longer Sans would stay asleep? It was too much of a risk.

As he contemplated that, he realized suddenly that he didn’t have to do too much to his brother’s dick. Instead, Sans’ hips had started to shift, the older brother fucking his fist unknowingly with little gasps of pleasure. They were small thrusts, not really much at all, but it was certainly enough for Papyrus’ libido.

“How can you be any more perfect, aniki?” Papyrus muttered, not noticing his slip-up, “Since when have you been so cute?”

Almost as if Sans could hear him, he squirmed a little, thrusting up just a bit harder in retaliation for being called cute. Papyrus held back a giggle.

Having gathered a satisfying amount of precum, Papyrus made sure his gloved fingers were slicked well enough, inspecting them. He stuck his fingers together, gazing at the blue cum and its contrast with his gloves. Something like that shouldn’t have been arousing, but he knew he was a little weird at that point.

Pushing those thoughts aside, he took a hold of Sans’ cock again with his right hand, his left reaching down. He started jacking his brother off again as the other groaned, Sans’ head turned toward his arm. The short skeleton’s pelvis twitched a little, too, when a finger started poking at his hole.

Papyrus was always careful with this sort of thing, never wanting to cause pain. So he pressed against Sans’ opening slowly until it allowed his finger in easily enough, pressing down on the intruder with soft, fluttering walls of magic.

“Does that feel good, aniki? Do you want more?”

“hhh…hah…”

Papyrus smiled teasingly, though the other couldn’t see it, “Well, you have to be patient. There’s no need to rush, you spoiled boy.”

Sans pulsed around his moving finger abruptly, groaning lowly, and Papyrus slowed down for a moment. Still, he’d file the use of “boy” away for later, once Sans wasn’t as close to consciousness at the moment.

Being safe, Papyrus waited for a few seconds to pass before he started moving again, his single finger searching for the spot so he could press again with two inside. His other hand dutifully clenched and released alternately, making sure he paid attention to every one of his dozing older brother’s needs.

Suddenly, Papyrus’ finger slid against a small, walnut-sized bump inside of Sans’ core, and the skeleton under him shook, a breathy gasp escaping through his teeth as his head pressed back.

“There we go…” Papyrus hummed, pressing again, “Do you want to be played with here, aniki?”

“ghhhmm~” Sans moaned lowly, his teeth unclenching briefly before his fangs were hidden again.

“I thought you would. Let me take care of you quickly, then.”

He pressed the second finger into the other, not really looking to stretch him so much as he was looking to get Sans to cum. He thrust them into his body once, twice, three times, then began his special attack, curling the tips of his fingers up, pressing and circling around his inner button.

“hahh! o-ooh! mmahh~ mmmh…”

Papyrus’ pelvis tingled and itched with a newfound vengeance at his moaning, but he wasn’t going to touch himself this time. Instead, he wanted to take in all of the little hidden faces Sans had, wanted to see the wonders the skeleton had been hiding from him. So he pressed his fingers into that bump again, and Sans whined lowly in his throat, his sternum trembling.

Sans’ ribcage was moving faster as he gasped unneededly, his hips unable to decide whether to push down onto the fingers rubbing around the inside of his core or pull away. His face was glowing with magic at that point, and a trail of drool had escaped his mouth down the left side. More than anything, though, Papyrus loved how vocal he was being.

“ahh… mmh~ hahh~ mmmahh~”

“So good, Sans…” Papyrus breathed, trembling, his own tentacle pressing around the inside of his shorts, “You’re doing so great.”

He prepped his fingers for a second, then gave one last, brutal press onto Sans’ insides.

“I love you so much, aniki.”

Sans’ back arched, choked moans filtering through his open jaws as his fangs gleamed with drool. His body trembled and twitched without control, breathy noises escaping him unchecked by consciousness.

“hhah! hmm! mmmhhhu…hhahh…”

Papyrus gazed at Sans’ hole as he squeezed down onto his fingers with one last whine. The tentacle in the other hand trembled and squirted, releasing his cum onto Pap’s fingers and his own stomach.

Papyrus choked on his own breath at the sight, harder than he could ever remember. He wanted so much to be in his own fingers’ place, to be the one hitting all of Sans’ spots inside and to make him cum. Still, he knew he was close enough as it was, wouldn’t last two seconds inside his brother, so he reached down and pressed the hand previously holding the other onto the front of his shorts. He came embarrassingly quickly, grunting behind his teeth.

The brothers were silent then, breathing into the heated air. Papyrus had reached a high greater than he’d expected from not actually having penetrative sex with his brother, but he certainly wasn’t going to complain. He’d have to remember the things Sans liked…once he could think.

But he wasn’t given enough time for that.

“…papyrrrs?”

The taller skeleton froze, his body jolting with shock. But surely enough, when his sockets looked down to Sans’, his were open enough for Papyrus to see his hazy, sleep riddled eyelights. Sans gave a grunt as he pushed himself up onto his elbows, looking down his chest at the rest of his body. His face flushed a deeper blue once he took in his half-nude form, noting the trail of blue that connected Pap’s gloved fingers to his lower half. He plopped onto his back.

“gh…geez, pap…what was…what did you…?” Sans murmured, still rubbing the sleep out of his sockets.

The younger skeleton felt his soul drop, and his body started to tremble very lightly for a completely different reason than just moments before, all arousal gone. “Oh, I…uhm…well, I admit that I didn’t consult you first as I should of. I didn’t want to wake you, since you seemed to be enjoying yourself so much.” He swallowed the ball of anxiety pressing against his sternum. “Was this…not okay?”

He knew he asked that question but really, what would he do if he said “no”? What would that make him? He knew he shouldn’t have done it in the first place, shouldn’t have looked at his brother’s prone form in such a way… Now…

Sans considered his younger brother sleepily, eyelights still hazy. Then he stretched his arms up, whining low in his skull, and turned as much onto his side as he could with Papyrus still between his legs.

“mmh…it’s cool, bro.”

Papyrus blinked, “What? Are you certain?”

Sans’ sleepy grin shifted a little wider, “yeah. it’s you, after all. i don’t mind if it’s you.”

For a second, the taller skeleton wasn’t sure what to say at the feeling of his soul practically bursting with gratefulness. He was ecstatic, even, and a part of him felt a tad silly. Concern was one thing, but maybe he shouldn’t have worried himself into a tizzy nearly as much as he just did.

With a jubilant flush of his cheekbones, Papyrus leaned forward and pressed his teeth against Sans’ cheekbone gratefully. The shorter skeleton hummed and turned his head a little so the next kiss was on his mouth.

“Thank you so much, brother! Still, I will be sure to get your affirmation ahead of time next time.”

Sans mumbled, “this is confirmation…what’d i say before? uhm…land…your…yeah. that. mmmhh…w’z good…”

“You’re still half-asleep, Sans,” Papyrus sighed, “I’ll ask you again when you wake up some more.”

Sans grunted, sleepily, shifting till his head was cradled in his left arm on the couch.

Papyrus laughed a little as he reached down, starting to pull Sans’ shorts back up his legs. “Ah, I’ve brought the groceries back. What do you want for dinner?”

When he didn’t get a reply, he looked back up toward the older skeleton’s face. Again, like he’d seen him before, his expression was slack, sockets closed, though there was still a bit of residual blue flush on his bones. A small snore escaped through the small gap between his front teeth.

Papyrus felt sweat run down the back of his skull, even while he grinned. “Just how tired are you? Lazy bones.”


End file.
